JP6134520B2 - Balance correction device and power storage device - Google Patents

Description

  The present invention relates to a balance correction device and a power storage device for equalizing voltages between power storage cells or between power storage modules composed of a plurality of power storage cells connected in series in an assembled battery composed of a plurality of power storage cells connected in series.

  In an assembled battery in which a plurality of power storage cells are connected in series, it is necessary to suppress variations in voltage (electromotive force) between the power storage cells in order to prevent a decrease in discharge capacity and a reduction in life. In particular, for an assembled battery composed of a large number of power storage cells, such as a power storage device used in an electric vehicle or the like, it is required to strictly suppress variations in voltage between the power storage cells.

  As a mechanism for equalizing the voltage between the storage cells, for example, in Patent Document 1, one end of the inductor L is connected to the connection point of the secondary batteries B1 and B2 connected in series, and the other end of the inductor L is connected. A first mode in which current flows through a first closed circuit formed by connecting to the other end of the battery B1, and a second closed circuit formed by connecting the other end of the inductor L to the other end of the battery B2. A balance correction method for equalizing the voltages of the battery B1 and the battery B2 by executing an operation (switching operation) that alternately repeats the second mode to be flown alternately for a short period of time is disclosed (hereinafter, the same). The balance correction method disclosed in the literature is called a converter method.)

  In Patent Document 2, in a battery pack used in a notebook computer or the like, a plurality of cells are connected in series in order to correct cell balance while reducing loss in the battery pack when the load current is small. An ON / OFF converter circuit in which the output voltage of these unit cells is input and the output is connected in the charging direction of each unit cell, and a current control circuit that increases or decreases the primary side current according to the magnitude of the load current The battery pack provided is disclosed (hereinafter, the balance correction method disclosed in the document is referred to as a transformer method).

JP 2001-185229 A JP-A-11-176483

  FIG. 6 shows a converter-type balance correction circuit 6 shown as an example of a balance correction device for ensuring the balance of the storage battery storage cells. As shown in the figure, the storage battery 3 is configured by connecting power storage cells B1 and B2 in series. The positive and negative terminals 31 and 32 of the assembled battery 3 have a current supply source (for example, a charger, a regenerative circuit) that supplies a charging current to the assembled battery 3 or a load (for example, a motor, a demand) that uses the power of the assembled battery 3. House load, electronic circuit).

  One end of the inductor L is connected to a line connecting the negative electrode of the storage cell B1 and the positive electrode of the storage cell B2. A switching element S1 is provided on the line connecting the other end of the inductor L and the positive electrode of the storage cell B1. A switching element S2 is provided on a line connecting the other end of the inductor L and the negative electrode of the storage cell B2.

  The switching elements S1 and S2 are configured using, for example, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). The switching elements S1 and S2 are configured such that when one switching element is turned on by the gate drivers D1 and D2 controlled by the control signals φ1 and φ2 generated by the control circuit 30, the other switching element is turned off. , Operate complementary to each other.

  As shown in the figure, a capacitive element C1 is provided between one end of the inductor L and the positive electrode of the storage cell B1, and a capacitive element C2 is provided between one end of the inductor L and the negative electrode of the storage cell B2. Each is provided. Capacitance elements C1 and C2 are provided for the purpose of, for example, reducing noise generated due to the on / off operation of the switching elements, and mitigating voltage changes that occur in power storage cells B1 and B2 due to switching. When the switching elements S1 and S2 are MOSFETs, the capacitive elements C1 and C2 may be parasitic capacitances of the switching elements S1 and S2.

  In the balance correction circuit having the above configuration, the control circuit 10 alternately controls the switching element S1 and the switching element S2 on and off at a predetermined duty ratio by a control signal. Thereby, power is transferred between the storage cell B1 and the storage cell B2, and the voltages of the storage cell B1 and the storage cell B2 are equalized.

  The control circuit 10 uses a voltage sensor (such as a voltmeter) to measure the voltages of the storage cells B1 and B2 (for example, the voltage between the connection points J4-J3 and the voltage between the connection points J3-J5 in the figure) in real time. Monitoring. The control circuit 10 stops the switching operation of the switching elements S1 and S2 when detecting that the voltages of both the storage cells B1 and B2 are substantially matched (cell balance is sufficiently secured).

  By the way, in the balance correction circuit 6 having the above-described configuration, even when a disconnection occurs at the disconnection portion 71 shown in FIG. 7 during the on / off control, for example, from the storage cell B2 toward the capacitive element C1. Since the energy is supplied, the potential of the connection point J4 hardly changes, and therefore the control circuit 10 cannot detect that the disconnection site 71 is disconnected. After that, as a result of the balance correction circuit 6 continuing the on / off control, there is a possibility that the variation in voltage between the storage cells B1 and B2 may be increased. Such a situation is the same when, for example, a disconnection occurs in a line connecting the negative electrode of the storage cell B1 and the connection point J3.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a balance correction device and a power storage device capable of reliably detecting disconnection occurring in a circuit.

  In order to achieve the above object, one of the present inventions is an assembled battery composed of a plurality of power storage cells connected in series, and between power storage cells or between power storage modules composed of a plurality of power storage cells connected in series. A balance correction device for equalizing voltages, wherein on / off control of current supply to each of the power storage modules with a first duty ratio allows the power storage modules to be connected via elements commonly connected to each other. A switching control unit that generates power between modules and equalizes the voltage between the power storage modules, and a duty that generates a period for performing the on / off control at a second duty ratio different from the first duty ratio A ratio control unit, a voltage measurement unit that measures a voltage applied to a capacitive element connected between the terminals of the storage cell, and the Based on the change of the voltage applied to the capacitive element between, and a disconnection detecting unit it determines the presence or absence of disconnection of the line connecting the said capacitive element and said energy storage cell.

  Another aspect of the present invention is the balance correction apparatus, wherein the disconnection detection unit is configured to detect the breakage when the time change rate of the voltage applied to the capacitive element exceeds a predetermined threshold during the period. It is determined that a disconnection has occurred in the line connecting the capacitive element and the storage cell.

  Another aspect of the present invention is the balance correction apparatus described above, in which an inductor has one end connected to a connection point between the first power storage module and the second power storage module that are connected back and forth, A first switching element connected in series with the inductor between the positive and negative terminals of the first power storage module; and a second switching element connected in series with the inductor between the positive and negative terminals of the second power storage module. And the switching control unit alternately turns on and off the first switching element and the second switching element to cause power to be transferred between the power storage modules via the inductor. Equalize the voltage between modules.

Another aspect of the present invention is the balance correction apparatus, wherein the first switching element and the second switching element are MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), and the capacitive element is , Parasitic capacitance existing in the first switching element or the second switching element.

  Another aspect of the present invention is the balance correction apparatus, wherein the primary winding connected between the positive and negative terminals of the battery assembly including the plurality of power storage modules connected in series, and each of the power storage modules. A transformer having a plurality of secondary windings connected between the positive and negative terminals, and a switching element connected in series to the battery assembly in a path including the battery assembly and the primary winding, and the switching control. The unit causes power to be transferred between the power storage modules through the transformer by performing on / off control of the switching element, and equalizes the voltage between the power storage modules.

  Another aspect of the present invention is a power storage device including the plurality of power storage cells connected in series and the balance correction device.

  In addition, the subject which this application discloses, and its solution method are clarified by the column of the form for inventing, and drawing.

  According to the present invention, it is possible to reliably detect disconnection generated in a circuit with a simple configuration.

1 is an example of a converter type balance correction circuit 1; (A) is a waveform of the control signals φ1 and φ2 output by the control circuit 10 in the first period, and (b) to (d) are waveforms of a current flowing through the inductor L in the first period. (A) is a waveform of the control signals φ1 and φ2 in the second period, (b) is a graph showing changes in voltage and current at a predetermined location of the balance correction circuit 1 when no disconnection occurs, (C) is a graph which shows the change of the voltage and electric current of the predetermined location of the balance correction circuit 1 when the disconnection has arisen. It is a figure which shows the disconnection part 41. FIG. 2 is an example of a transformer type balance correction circuit 2; It is an example of the balance correction circuit 6 of a converter system. It is a figure which shows the disconnection location 71. FIG.

  Hereinafter, embodiments of the present invention will be described. In the following description, the same or similar parts may be denoted by the same reference numerals and redundant description may be omitted.

  FIG. 1 shows a balance correction circuit 1 (balance correction apparatus) shown as an embodiment of the present invention. The balance correction circuit 1 includes, for example, a power storage device (an electric vehicle, a hybrid vehicle, an electric two-wheeled vehicle, a railway vehicle, an elevator, a power storage device for system linkage, a personal computer, which uses an assembled battery including a plurality of power storage cells connected in series. (Notebook computers, mobile phones, smartphones, PDA devices, etc.) The power storage cell is typically a lithium ion secondary battery, a lithium ion polymer secondary battery, or the like, for example, but the power storage cell may be another type of power storage element such as an electric double layer capacitor.

  When the manufacturing quality and the degree of deterioration are different between the storage cells constituting the assembled battery, there may be a difference in battery characteristics (battery capacity, discharge voltage characteristics) between the storage cells. Due to such difference in battery characteristics, the voltage between the storage cells may vary during charging and discharging. Therefore, in order to suppress the occurrence of such variation, the balance correction circuit 1 equalizes the voltage between the storage cells or the voltage between the storage modules composed of a plurality of storage cells connected in series (ensuring cell balance). To work.

  As shown in the drawing, the storage cells B1 and B2 are connected in series to form the battery assembly 3. The positive and negative terminals 31 and 32 of the assembled battery 3 have a current supply source (for example, a charger, a regenerative circuit) that supplies a charging current to the assembled battery 3 and a load that functions using the electromotive force of the assembled battery 3 (for example, Motor, consumer load, electronic circuit) and the like are connected.

  One end of the inductor L is connected to a line connecting the negative electrode of the storage cell B1 and the positive electrode of the storage cell B2. A switching element S1 is provided on a line connecting the other end of the inductor L and the positive electrode of the storage cell B1. A switching element S2 is provided on a line connecting the other end of the inductor L and the negative electrode of the storage cell B2.

  The switching elements S1 and S2 are configured using MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors). The switching elements S1 and S2 are turned off when one switching element is turned on by the gate drivers D1 and D2 controlled by the control signals φ1 and φ2 generated by the control circuit 10 (switching control unit). Operate in a complementary manner.

  A capacitive element C1 is provided between one end of the inductor L and the positive electrode of the storage cell B1, and a capacitive element C2 is provided between one end of the inductor L and the negative electrode of the storage cell B2. Capacitance elements C1 and C2 are provided for the purpose of, for example, reducing noise generated due to the on / off operation of the switching elements, and mitigating voltage changes that occur in power storage cells B1 and B2 due to switching. When the switching elements S1 and S2 are MOSFETs, the capacitive elements C1 and C2 may be parasitic capacitances of the switching elements S1 and S2. The capacitive element C1 may be provided between the connection point J4 and the connection point J5 (both terminals of the capacitive element C1 are connected to the connection point J4 and the connection point J5, respectively).

  As shown in the figure, the control circuit 10 includes a control signal generation circuit 101, a duty ratio control circuit 102, a measurement circuit 103 (voltage measurement unit), and a disconnection detection circuit 104 (disconnection detection unit).

  The control signal generation circuit 101 generates two-phase control signals φ1 and φ2 to be supplied to the gate drivers D1 and D2, respectively. In the present embodiment, the control signals φ1 and φ2 are two-phase square waves (for example, PWM pulse (PWM: Pulse Width Modulation)) having a predetermined duty ratio (for example, 50%).

  The duty ratio control circuit 102 controls the duty ratio of the control signals φ1 and φ2 generated by the control signal generation circuit 101. The measurement circuit 103 acquires the measurement value of the voltage and the measurement value of the current in real time in a predetermined part of the line constituting the balance correction circuit 1.

  The disconnection detection circuit 104 configures the balance correction circuit 1 on the basis of the time change rate (voltage change amount per unit time) of a predetermined portion of the line constituting the balance correction circuit 1 in the second period. Detects the presence or absence of disconnection on the line. For example, the disconnection detection circuit 104 determines whether or not the time change rate (voltage change amount per unit time) of the voltage applied between the terminals of the capacitor elements C1 and C2 exceeds a predetermined threshold value. , C2 and the storage cell B1 or B2, the presence or absence of disconnection in the line is detected.

  Next, the basic operation of the balance correction circuit 1 will be described with reference to FIG.

  FIG. 2A shows the waveforms of the control signals φ1 and φ2 generated by the control circuit 10 during the period when the on / off control of the switching elements S1 and S2 is performed. As shown in the figure, during the period, the control circuit 10 generates control signals φ1 and φ2 composed of square waves that are complementarily turned on and off in the same cycle, for example.

  2B to 2D are waveforms of the current iL flowing through the inductor L during the period when the on / off control of the switching elements S1 and S2 is performed. Of these, FIG. 2B shows a waveform of the current iL flowing through the inductor L when the voltage E1 of the storage cell B1 is larger than the voltage E2 of the storage cell B2, and FIG. 2C shows the voltage of the storage cell B1. FIG. 2D shows the waveform of the current iL flowing through the inductor L when E1 is smaller than the voltage E2 of the storage cell B2, and FIG. 2D shows that the voltage E1 of the storage cell B1 and the voltage E2 of the storage cell B2 are equal ( This is a waveform of the current iL flowing through the inductor L in the case of substantially equal).

  Here, as shown in FIG. 2B, when the voltage E1 of the storage cell B1 is larger than the voltage E2 of the storage cell B2 (E1> E2), the switching element S1 is on and the switching element S2 is off. Mainly, the positive electrode of the storage cell B1, the connection point J6, the connection point J4, the switching element S1, the inductor L, the connection point J3, the connection point J1, and the negative electrode path of the storage cell B1 (hereinafter referred to as a first path). ) Current iL flows. That is, during this period, current iL flows mainly in the direction of the solid line arrow shown in FIG.

  Thereafter, when the switching element S1 is turned off and the switching element S2 is turned on, the energy stored in the inductor L is changed from the inductor L → the connection point J3 → the connection point J1 → the positive electrode of the storage cell B2 → the negative electrode of the storage cell B2. It is discharged through a path of point J7 → connection point J5 → switching element S2 → inductor L, whereby the storage cell B2 is charged. When the energy of the inductor L is lost, the current iL starts to flow through the inductor L in the reverse direction.

  Also, as shown in FIG. 2C, when the voltage E1 of the storage cell B1 is smaller than the voltage E2 of the storage cell B2 (E1 <E2), during the period when the switching element S1 is off and the switching element S2 is on, Mainly the positive electrode of the storage cell B2, the connection point J1, the connection point J3, the inductor L, the connection point J2, the switching element S2, the connection point J5, the connection point J7, and the negative electrode path of the storage cell B2 (hereinafter referred to as the second path). Current iL flows. That is, during this period, current iL flows mainly in the direction of the broken line arrow shown in FIG.

  Thereafter, when the switching element S2 is turned off and the switching element S1 is turned on, the energy stored in the inductor L is changed from the inductor L → the connection point J2 → the switching element S1 → the connection point J4 → the connection point J6 → the positive electrode of the storage cell B1. → The negative electrode of the storage cell B1 → the connection point J1 → the connection point J3 → discharged through the inductor L, whereby the storage cell B1 is charged. When the energy of the inductor L is lost, the current iL starts to flow through the inductor L in the reverse direction.

As described above, when there is a difference in the voltage between the storage cells B1 and B2, the current iL alternately flows through the first path and the second path, thereby transferring energy between the storage cell B1 and the storage cell B2. As a result, the voltages of both are equalized to ensure cell balance. As shown in FIG. 2D, when the voltage E1 of the storage cell B1 and the voltage E2 of the storage cell B2 are equal (E1 = E2), the power is transferred between the storage cells B1 and B2 in accordance with the on / off control. The balance of energy balance is balanced, and the voltage between the storage cells B1 and B2 is kept uniform.

  The control circuit 10 determines the voltage measured by the measurement circuit 103 (the voltage between the terminals of the storage cells B1 and B2 (for example, the voltage between the connection points J4-J3, the voltage between the connection points J3-J5, etc.). When monitoring in real time and detecting that the voltages of the storage cells B1 and B2 are equal (substantially match), the on / off control of the switching elements S1 and S2 is stopped.

<Disconnection detection>
Subsequently, a mechanism of disconnection detection by the balance correction circuit 1 of the present embodiment will be described. When the control circuit 10 determines that it is necessary to ensure the cell balance between the storage cells B1 and B2, the control circuit 10 outputs the control signals φ1 and φ2 having the first duty ratio (for example, 50%) to output the switching elements S1 and S2. Is turned on and off, and power is transferred between the storage cells B1 and B2 to equalize the voltage between the storage cells B1 and B2.

  On the other hand, in order to detect disconnection in the line, the control circuit 10 has a second duty ratio (for example, 70) different from the first duty ratio in the on-off control period (hereinafter referred to as the first period). A period (hereinafter referred to as a second period) in which the control signals φ1 and φ2 composed of ˜90% are output repeatedly at predetermined intervals. For example, the control circuit 10 sets the time interval and the period so as not to affect the equalization of the cell balance by the balance correction circuit 1 and generates the second period.

  FIG. 3A shows an example of the control signals φ1 and φ2 output from the control circuit 10 in the first period and the second period. In the figure, the period from time t1 to t3 corresponds to the first period, and the period from time t3 to t6 corresponds to the second period. Here, in the second period, the time change rate of the voltage applied between the respective terminals of the capacitive elements C1 and C2 is remarkable depending on whether the line of the balance correction circuit 1 is disconnected or not. There is a big difference. Hereinafter, the case where the disconnection part 41 shown in FIG. 4 (predetermined part of the line connecting the connection point J4 of the balance correction circuit 1 and the positive electrode of the storage cell B1) is broken will be described as an example.

  FIG. 3B shows a voltage change at a predetermined position of the balance correction circuit 1 measured by the measurement circuit 103 when the balance correction circuit 1 is not disconnected, as shown on the same time axis as FIG. And it is a graph which shows an electric current change. In FIG. 3, Va is the voltage of the line connected to the switching element S1 side with respect to the broken portion 41 (the voltage of the terminal connected to the positive electrode of the storage cell B1 of the capacitive element C1) (see FIG. 4), Vb Is the voltage of the line connected to the positive electrode of the storage cell B1 with respect to the disconnection part 41, and Ib is the current flowing through the line connected to the positive electrode of the storage cell B1 with respect to the disconnection part 41 described later. The reference potential when measuring Va and Vb is, for example, the connection point J3 and the connection point J5.

  As shown in FIG. 3B, when no breakage occurs in the balance correction circuit 1, all of Va, Vb, and Ib gradually increase over time during the second period. .

  FIG. 3C is a graph showing temporal changes in Va, Vb, and Ib indicated on the same time axis as that in FIG. 3A when the disconnection portion 41 is disconnected. As shown in the figure, when a disconnection occurs in the disconnection portion 41, no current flows through the line connecting the connection point J4 and the positive electrode of the storage cell B1, and therefore both Vb and Ib remain constant. It is. However, since a current flows into the capacitive element C1 by the switching operation, the value of Va increases rapidly (in particular, the period from time t3 to t5 in the figure).

  In this way, by checking whether or not the time change rate of Va in the second period exceeds a predetermined threshold, it is ensured that there is no disconnection in the line connecting the connection point J4 and the positive electrode of the storage cell B1. Can be detected. By the same mechanism as described above, it is possible to detect disconnection in the line connecting the connection point J5 and the negative electrode of the storage cell B2, and disconnection in the line connecting the connection point J3 and the positive electrode of the storage cell B2. it can.

  As described above, according to the balance correction circuit 1 of the present embodiment, the disconnection in the circuit can be reliably detected with a simple configuration. Even if the duty ratio is changed during the switching operation in this way, the mechanism of overcharge monitoring control and overdischarge monitoring control provided in a general balance correction device operates, so that the storage cells B1, B2 The voltage will not rise or fall extremely.

  By the way, description of embodiment described above is for making an understanding of this invention easy, and does not limit this invention. It goes without saying that the present invention can be changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof.

  For example, in the above embodiment, the second duty ratio is set higher than the first duty ratio, but the second duty ratio may be set lower than the first duty ratio. In this case, for example, if a disconnection occurs in the disconnection part 41 shown in FIG. 4, the value of Va rapidly decreases. Therefore, the presence or absence of the disconnection may be determined by detecting this.

  As the measurement circuit 103, an existing voltage sensor or current sensor for detecting the cell balance (voltage difference) of the storage cell or the cell module can be used. For this reason, the balance correction circuit 1 of the present embodiment can be realized simply and at low cost.

  The balance correction circuit of the present invention may be provided separately from the storage cell, or may be integrated with the storage cell to form a battery pack or the like.

  In the above-described embodiment, the converter type balance correction circuit 1 has been described as an example. However, the present invention can also be applied to a transformer type balance correction circuit.

  FIG. 5 shows an example of a transformer type balance correction circuit 2 to which the present invention is applied. As shown in the figure, the battery cell B1 and the battery cell B2 are connected in series to form the battery assembly 3. A charging current supply source or a load is connected between the positive and negative terminals of the assembled battery 3. Between the positive and negative terminals of the assembled battery 3, the primary winding N <b> 1 of the transformer Tr and the switching element S are connected. A secondary winding N2 of the transformer Tr is connected between the positive and negative terminals of each of the storage cells B1, B2.

  Rectifying elements d1 and d2 are provided on paths formed by the storage cells B1 and B2 and the secondary winding N2 connected between the positive and negative terminals, respectively. Capacitance elements C1 and C2 are connected between the positive and negative terminals of the storage cells B1 and B2, respectively. The capacitive elements C1 and C2 are provided for the purpose of, for example, reducing noise generated from the transformer Tr and the elements, mitigating voltage changes occurring in the storage cells B1 and B2, and the like.

  The switching element S is ON / OFF controlled by a control signal generated by the control circuit 20. Similar to the control circuit 10 described above, the control circuit 20 includes a control signal generation circuit 201, a duty ratio control circuit 202, a measurement circuit 203, and a disconnection detection circuit 204.

  The control signal generation circuit 201 generates a control signal for on / off control of the switching element S. The switching element S is configured using, for example, a MOSFET or a bipolar transistor. When the switching element S is composed of a bipolar transistor, the control signal is input to the base. When the switching element S is composed of a MOSFET, the control signal is input to the gate.

  In this balance correction circuit 2, the power of the battery assembly 3 composed of the storage cells B1 and B2 connected in series is redistributed from the primary winding N1 to the secondary windings N2, thereby storing the storage cell B1. , B2 are equalized.

  As in the case of the converter method described above, the presence / absence of disconnection in the disconnection portion 51 shown in the figure is determined by examining whether the time change rate of Va in the second period described above exceeds a predetermined threshold value. . Further, as in the case of the converter method described above, the presence or absence of disconnection in the line connecting the capacitive element C1 and the negative electrode of the storage cell B1, the presence or absence of disconnection in the line connecting the capacitive element C2 and the positive electrode of the storage cell B2, It is also possible to determine whether or not there is a break in the line connecting the capacitive element C2 and the negative electrode of the storage cell B2.

  DESCRIPTION OF SYMBOLS 1 Balance correction circuit, 10 Control circuit, 41 Disconnection part, 101 Control signal generation circuit, 102 Duty ratio control circuit, 103 Measurement circuit, 104 Disconnection detection circuit, L inductor, C1, C2 capacitive element, B1, B2 storage cell, S1 , S2 switching element

Claims (6)

In an assembled battery composed of a plurality of power storage cells connected in series, a balance correction device for equalizing a voltage between the power storage cells or between power storage modules composed of a plurality of power storage cells connected in series,
By controlling on / off of current supply to each of the power storage modules with a first duty ratio, power is transferred between the power storage modules via elements commonly connected to the power storage modules, and the power storage A switching controller that equalizes the voltage between the modules;
A duty ratio control unit that generates a period for performing the on / off control at a second duty ratio different from the first duty ratio;
A voltage measuring unit for measuring a voltage applied to a capacitive element connected between terminals of the storage cell;
A disconnection detector for determining the presence or absence of a disconnection of a line connecting the capacitive element and the storage cell based on a change in the voltage applied to the capacitive element in the period;
A balance correction device comprising:   The disconnection detection unit determines that a disconnection has occurred in a line connecting the capacitive element and the storage cell when a time change rate of the voltage applied to the capacitive element exceeds a predetermined threshold during the period. The balance correction apparatus according to claim 1. An inductor having one end connected to a connection point between the first power storage module and the second power storage module that are connected back and forth, and the inductor connected in series between the positive and negative terminals of the first power storage module A first switching element and a second switching element connected in series with the inductor between the positive and negative terminals of the second power storage module;
The switching control unit alternately turns on and off the first switching element and the second switching element, thereby causing power to be transferred between the power storage modules via the inductor, so that the power storage modules The balance correction apparatus according to claim 1 or 2, wherein the voltage is equalized. The first switching element and the second switching element are MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), and the capacitive element is present in the first switching element or the second switching element. The balance correction device according to claim 3, wherein the balance correction device is a parasitic capacitance. A transformer having a primary winding connected between positive and negative terminals of an assembled battery composed of a plurality of power storage modules connected in series, and a plurality of secondary windings connected between positive and negative terminals of the power storage module And a switching element connected in series to the battery assembly in a path including the battery assembly and the primary winding,
The switching control unit causes the power to be exchanged between the power storage modules via the transformer by performing on / off control of the switching element, and equalizes the voltage between the power storage modules.
The balance correction apparatus according to claim 1.   A power storage device comprising the plurality of power storage cells and the balance correction device according to any one of claims 1 to 5.

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